So... you have 60-75 watts to work with. That means, with the right wire, you can go down to around 0.3Ω or slightly less.
Do you have an accurate Ohm meter/build box? Not resolution, but accuracy can be critical as you dip down below 0.25Ω or so.
0.05Ω off to the low side and the amperage requirements increase rapidly.
It's not a too serious concern with a PV that has a low resistance baby sitter... more so if you were using a unregulated mech.
That low resistance baby sitter is why I'm going to offer some suggestions... if you were a mech user, I'd tell you nothing, because you probably don't know much about Ohm's law and battery safety. Not a dig... just that you wouldn't be asking such basic questions if you did.
I'll use 60 watts, because that's guaranteed... above that, I don't know.
There are literally hundreds of possible builds within the following range... each with slightly different variables. This is just one. Builds are best fine tuned for the individual user, atomizer air flow potential, wick type and juice blend being used.
24 gauge Kanthal A-1, dual parallel coils at 0.30Ω net resistance. This would be 7/6 wraps on a 7/64" (2.78mm) mandrel, with an estimated 5mm per coil of net leg length. Performance specs are:
- Coil surface area, per coil - 127.86 mm². Good combination for flavor and vapor density, in a "mini" RDA.
- Coil radiant heat (at 60 watts) - 221 mW/mm². More than adequate... a bit warm for some, but certainly not hot.
- Heat capacity, per coil 56.65 mJ/K. "Time to temperature" - not instant, but quick enough that you won't grow a beard waiting for it.
- Leg power loss - 5.9 %. Acceptable.
Fit cotton wicking to be low density/compression, and a "slight drag" pulled through the coil.
Fine tune, per this Steam Engine build sheet, as needed to increase/decrease variable values. Read the article found at the end of the first hyperlink sigline below... for a better understanding of performance variables.
